U.S. patent number 4,016,464 [Application Number 05/674,203] was granted by the patent office on 1977-04-05 for anode riser means for a capacitor.
This patent grant is currently assigned to P. R. Mallory & Co., Inc.. Invention is credited to Paul S. Deak, Gerald A. Voyles.
United States Patent |
4,016,464 |
Voyles , et al. |
April 5, 1977 |
Anode riser means for a capacitor
Abstract
A porous dielectric oxide film-forming metal anode capacitor is
provided with an anode riser means that is able to absorb energy by
deforming or flexing when subjected to compressive forces such as
the forces resulting from a crimping operation in the construction
of the capacitor. The anode riser means comprises one or more
continuous lengths of metal with at least a portion of one of the
lengths in the shape of a bight.
Inventors: |
Voyles; Gerald A.
(Indianapolis, IN), Deak; Paul S. (Indianapolis, IN) |
Assignee: |
P. R. Mallory & Co., Inc.
(Indianapolis, IN)
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Family
ID: |
27054055 |
Appl.
No.: |
05/674,203 |
Filed: |
April 5, 1976 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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502201 |
Aug 30, 1974 |
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Current U.S.
Class: |
361/510;
174/520 |
Current CPC
Class: |
H01G
9/008 (20130101) |
Current International
Class: |
H01G
9/00 (20060101); H01G 009/00 () |
Field of
Search: |
;317/230 ;174/52.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lynch; Michael J.
Assistant Examiner: Clawson, Jr.; Joseph E.
Attorney, Agent or Firm: Hoffmann, Meyer & Coles
Parent Case Text
This is a continuation of application Ser. No. 502,201, filed Aug.
30, 1974, now abandoned.
Claims
We claim:
1. A capcitor comprising a housing having an open end, a sintered
dielectric oxide film-forming metal anode means having a myriad of
intercommunicating voids, a liquid type electrolyte contacting the
anode means, rigid means closing the open end of the housing and
edges of the housing compressively acting on the rigid means and
thereby on the anode means, resilient means interposed between the
anode means and the rigid means, surfaces of the resilient means
contacting the anode means and the rigid means to help maintain the
anode means in the fixed spatial relationship relative to the
housing, and anode riser means capable of absorbing compressive
forces projecting through the resilient means, the anode riser
means having two distal ends and comprising at least one continuous
length of metal and at least a portion of at least one length in
the shape of a bight, the first distal end of the anode riser means
in electrical contact with the anode means and the second distal
end providing means for external termination of the anode
means.
2. The capacitor of claim 1, wherein the anode riser means has a
substantially C-shaped portion.
3. The capacitor of claim 1, wherein the anode riser means has a
substantially S-shaped portion.
4. The capacitor of claim 1, wherein the anode riser means contains
two lengths of metal connected together and forming at least two
substantially right angles.
5. The capacitor of claim 1, wherein the anode riser means contains
three lengths of metal connected together, an intermediate length
forming angles with two other lengths.
Description
The present invention relates to electrical devices and more
particularly, to porous dielectric oxide film-forming metal anode
capacitors utilizing a liquid or semi-liquid electrolyte.
Porous dielectric oxide film-forming metal anode electrolytic
capacitors have gained wide acceptance in the electronics industry
because of their excellent performance characteristics and
particularly because of the high capacitance-voltage per unit of
volume of such devices. These devices generally comprise a porous
sintered dielectric oxide film-forming metal anode body, a metal
lead wire or riser embedded in the anode body and extending
therefrom, a dielectric oxide film over the anode body, a liquid or
semi-liquid electrolyte contacting the oxide film or the anode body
and acting as a cathode for the capacitor, a metallic housing or
can containing the electrolyte and the anode and in electrical
contact with the electrolyte, and an electrically insulative rigid
end seal assembly closing an open end of the housing, the anode
riser projecting through or in electrical contact with the end seal
assembly. Typically, the anode riser is composed of the same metal
as is used in the anode since the riser must be protected from
electrical contact with the electrolyte and this end can be
accomplished by forming a dielectric oxide film over the anode
riser. External electrical contact to the cathode is made by a
metal lead attached to the housing.
Dielectric oxide film-forming metals typically used to make a
porous anode for this type of capacitor are tantalum, niobium and
titanium. Tantalum is the most widely used metal of the three
because of generally more favorable electrical properties.
The end seal assembly of the housing has three primary functions,
one, to electrically insulate the anode riser from the metallic
housing, two, to prevent the leakage or loss of the electrolyte
from the capacitor during normal operating conditions, and three,
to help maintain the anode body in a fixed position relative to the
housing so that the capacitor is able to withstand vibrational
energy without harmful effects.
To fulfill the third function, the end seal assembly is usually
forced against the top of the anode body by crimping the open end
of the metal housing over the end seal assembly. The amount of
force utilized in crimping is fairly critical as not enough force
will result in capacitor that may not withstand vibrational energy
or may not retain electrolyte, and too much force may result in
harmful stresses on the anode or the anode riser. Unfortunately,
the amount of force used in the crimping operation is difficult to
accurately control, especially in small capacitors, and as a
consequence, many capacitors are overcrimped, that is, excess
compressive forces are utilized to close the housing. The forces
associated with such an overcrimping may cause damage to the anode
riser since the riser is fixed at both ends, one end at the anode
body and another in the end seal assembly. These forces may cause
buckling of the riser and breaks in the dielectric oxide layer of
the anode riser which may allow electrolyte to contact bare
tantalum metal and thereby cause a high leakage current, or even a
short, when the capacitor is in operation.
Even if the anode riser itself is not damaged by the excess
crimping forces, the integrity of the bond between the riser and
the end seat assembly may be harmfully affected by the compressive
forces thereby allowing a means for the loss of electrolyte and the
ingress of harmful contaminants. The electrical connection between
the anode body and the anode riser may also be harmfully affected
by the excess compressive forces due to loosening of the mechanical
connection between the two components.
It is therefore a feature of the present invention to reduce
compressive stresses experienced by the anode riser of a capacitor
due to engaging the seal with the housing are reduced. Another
feature of the invention is that the harmful effect of excess
crimping forces is reduced. Yet another feature of the invention is
that assembly of a tantalum electrolytic capacitor is
simplified.
These and various other features of this invention as well as many
specific advantages will become more fully apparent from a detailed
consideration of the remainder of this disclosure including the
accompanying drawings, in which;
FIG. 1 is a cross-sectional view of one embodiment of the
construction of a capacitor according to this invention.
FIG. 2 is a cross-sectional view of another embodiment of the
construction of a capacitor according to this invention.
FIG. 3 is a cross-sectional view of yet another embodiment of
construction of a capacitor according to this invention.
Generally, the present invention comprehends a deformable or
flexible anode riser means cooperatively associated with a porous
dielectric oxide film-forming metal anode electrolytic capacitor to
help minimize compressive stresses caused by the housing engaging
the seal of the capacitor such as experienced in a crimping
operation on the housing. More specifically, the present invention
relates to an anode riser means capable of absorbing energy having
two distal ends and comprising one or more continuous lengths of
metal and at least a portion of one length in the shape of a bight,
the first distal end of the anode riser means in electrical contact
with the anode and the second distal end providing means for
external electrical termination of the anode means. The shape of a
bight can be defined as one or more bends or curves in an object
such as loops, semi-loops, C-shapes, S-shapes, acute or obtuse
angles and the like. Thus the anode riser means has at least a
portion of its length having one or more curves and/or angles which
can be contrasted to a linear, axial anode riser means. An anode
riser means in this configuration is thereby able to flex or deform
and thereby absorb energy when the anode riser is under stress and
therefore helps to prevent damage to the capacitor during
construction, especially during the crimping operation. The
particular shape of the anode riser means is not critical, just so
long as it is able to flex or deform under compressive forces, is
readily manufactured, and is compatible with the end seal
assembly.
The concept of the invention can be more clearly understood with
reference to the accompanying drawing. FIG. 1 illustrates one
embodiment of the invention in a cross-sectional view of an
electrolytic tantalum capacitor 10. Capacitor 10 comprises a
sintered porous tantalum anode 11 partially retained in a rigid
metallic housing 12 by insulative bottom cup 13. A liquid or
semi-liquid electrolyte 14 is contained in the housing 12 and
contacts anode 11. Connection to the cathodic side of the capacitor
10 is accomplished by cathode connection 25 which is in electrical
contact with the housing 12. End seal assembly 15 comprises a
elastomeric disc 16, an elastomeric end plug 17 and a rigid seal 18
of the glass-to-metal type. The metal portion 19 of the seal 18 is
attached to the housing 12 and glass portion 20 of the seal is
around a part of the anode riser means 21. Anode riser means 21 is
composed of the terminal or feed-through portion 22 attached to the
energy absorbing portion 23 which is in the shape of a bight. In
this embodiment, the energy absorbing portion 23 of the anode riser
means 21 is generally C-shaped. In the construction of the
capacitor 10, the energy absorbing portion 23 will help relieve
stresses on the anode riser means 21 as the edges 24 of the housing
12 are crimped over the glass-to-metal seal 18. To complete
construction of capacitor 10, the edges 24 of the housing 12 are
joined by methods such as soldering or welding to the metal 19 of
the seal 18 by joint 26.
To facilitate the construction of the end seal assembly 15, the
elastometric plug 17 and/or the elastomeric disc 16 may contain a
slit or aperture 27 so that these components can be easily placed
in their proper position around the anode riser means 21,
especially the energy absorbing portion 23.
It should be understood that the various components of the
capacitor 10 as shown are given for illustrative purposes only and
the invention as described is not limited to this particular
combination of components. For example, the rigid seal may be a
glass-to-metal-to-ceramic seal, a ceramic-to-metal-seal, a
thermoplastic seal, a thermosetting seal or the like. Also, the
porous anode may be composed of other film-forming metals such as
niobium or titanium.
FIG. 2 illustrates another embodiment of an anode riser means which
is able to absorb the compressive forces of crimping without
substantial adverse effect. Capacitor 30 contains the same
components as shown in FIG. 1 except that the anode riser means is
of a different configuration. Anode riser means 31 is composed of
terminal or feed-through portion 32 and energy-absorbing portion 33
fastened together at point 34 to provide good electrical contact.
One part of energy absorbing portion 33 is embedded in anode 41,
offset from the vertical axis of the anode and the other part of
the energy absorbing portion contains an approximate right angle
bend thereby allowing for a certain amount of deflection during the
crimping operation. Again the elastomeric plug 37 and/or the
elastomeric disc 36 may be provided with a slit or aperture 38 to
facilitate the construction of the end seal assembly 35.
FIG. 3 illustrates yet another embodiment of an anode riser means
in a tantalum capacitor according to this invention. Again,
capacitor 50 contains the same components as shown in FIG. 1 except
for the anode riser means. Here anode riser means 51 comprises a
terminal or feed-through portion 52 with the glass 60 of the
glass-to-metal seal 58 around it, anode portion 53 partially
embedded in the anode, and connecting or energy absorbing portion
54 substantially S-shaped suitably affixed to the terminal portion
and the anode portion by means such as welding. Again the
elastomeric plug 57 of the end seal assembly 55 may contain a slit
or aperture 62 to facilitate construction of the capacitor 50.
The embodiments of an anode riser means according to this invention
as shown in the drawing are given for purposes of illustration only
and are not intended to limit the scope of the invention. The
skilled practitioner in the art, aware of the concepts of this
invention, could conceive many alternate structures or
configurations that are not here shown which could perform the
functions required equally as well.
Thus the invention as has heretofore been described comprehends an
anode riser means structure which is able to withstand harmful
compressive forces generated during the crimping operation in the
construction of an electrolytic dielectric oxide film-forming metal
anode capacitor. The anode riser means structure comprises at lease
one continuous length of metal with a substantial portion of the
riser means in the shape of a bight which allows the riser means to
absorb at least some potentially harmful compressive forces.
While the present invention has been described with reference to
particular embodiments thereof, it will be understood that numerous
modifications may be made by those skilled in the art without
actually departing from the spirit and scope of the invention as
defined in the appended claims.
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